Technical Field
The present disclosure relates to a medical hollow needle assembly obtained by joining a hollow metal needle to a resin outer cylindrical body, such as a syringe with a needle, an injection needle, an indwelling needle, or a butterfly needle, and further to a method of manufacturing a hollow needle used for a medical instrument.
Background Art
Syringes with needles have been used as medical instruments for injection, blood sampling, or the like to or from a living body such as a human body. As a syringe with a needle, a syringe with a fixed needle and a syringe with a detachable needle are known. A syringe with a fixed needle is configured so that a hollow metal needle is directly joined to a port of a resin syringe body. A syringe with a detachable needle is configured so that an injection needle is obtained by joining a hollow metal needle to a distal end of a resin hub (needle hub), and the hub is joined to a port of a syringe body. In an injection needle used for such a syringe with a fixed needle or a syringe with a detachable needle, the hollow metal needle is joined to the port of the syringe body or a resin outer cylindrical body such as the hub, and is configured as a hollow needle assembly. In this configuration, the hollow needle is configured so that an outer peripheral surface of a proximal end side portion of the hollow needle is joined to an inner peripheral surface of the port of the syringe body or an inner peripheral surface of the resin cylindrical body such as the hub, and the hollow needle is fixed to the cylindrical body.
As a method of manufacturing a hollow needle used for such a medical instrument, the following method is known. The method includes punching out a plate body having a predetermined shape from a metal plate such as a stainless steel sheet, rolling the plate body in a mold to be molded into a tubular body, joining a seam portion of the molded tubular body by welding, bonding, or the like, and forming the hollow needle.
In order to prevent removal of the hollow needle from the outer cylindrical body and secure safety, such a hollow needle assembly or a medical instrument must have the hollow needle joined to the outer cylindrical body with a joint strength not less than a predetermined value relative to a tensile load. Therefore, a configuration for joining the hollow needle and the outer cylindrical body with an adhesive has been generally employed. However, in this configuration, the adhesive used for joining is likely to make contact with a drug solution, blood, or the like to change the quality of the drug solution or negatively impact a human body, and there is a problem that in a joining step, checking process, or the like, the presence or absence of adhesion of the adhesive to the hollow needle or the like needs to be strictly managed.
Therefore, for example, as disclosed in JP 2004-154210 A, a configuration has been proposed that involves fixedly press-fitting an inner cylindrical body having a tapered outer surface and inserting one end of a hollow needle therein into a through-hole of an outer cylindrical body, in which an outer peripheral surface of the one end of the hollow needle is roughened by blasting or the like to cause an anchor effect on a joining surface, and the hollow needle is rigidly joined to the inner cylindrical body without an adhesive.
In this configuration, a plate body punched out from a metal plate is molded into a tubular body by pressing, a seam portion thereof is joined to form a hollow needle, and the outer peripheral surface of the hollow needle is further subjected to blasting. Thus, the anchor effect is generated at a joining portion between the hollow needle and the cylindrical body, and the hollow needle is rigidly joined to the cylindrical body without an adhesive.